In an exchange of mid-level prospects, the Royals shipped Triple-A reliever Carlos Rosa to the Diamondbacks for high Class A shortstop Rey Navarro.

Arizona ranks dead last in baseball with its seven-plus bullpen ERA and just lost righthander Leo Rosales for at least two months with a foot injury. Rosa will report to Triple-A Reno, but he might not remain there long as he waits for middle-innings work in Phoenix.

Of course, the Royals' bullpen has notched the second-worst ERA in the game and has featured a revolving cast of characters in the middle innings. Out: Roman Colon (designated for assignment), Juan Cruz (released), Luis Mendoza (DFA) and John Parrish (disabled list). In: Bruce Chen, Victor Marte, Josh Rupe and Brad Thompson. Given that any team could have had any of these relievers for a song, it's apparent that Rosa's future in Kansas City was dim. He remained stationed in Omaha even with the tumult.

The Royals shifted Rosa to the bullpen with Omaha in 2009 because it better suited his repertoire—a low- to mid-90s fastball and fringy secondary stuff. It worked insofar as Rosa registered his highest career strikeout rate (10.1 per nine innings) and put together 15 strong outings after the all-star break. In that stretch, he compiled a 31-to-8 strikeout-to-walk ratio in 25 2/3 innings, allowing only one home run. More telling perhaps was his ratio of 3.4 groundouts for every flyout. However, Rosa struggled to get warmed up on short notice and pitched in back-to-back games on only one occasion all year, which included stints in Kansas City and in the Dominican League. The strong-armed Rosa sits at 92-94 mph and frequently hits the mid-90s, with a fair amount of life, coming out of the pen. Rosa's mid-80s slider more resembles a cut fastball, with its short, one-plane break, and he never has shown much feel for a changeup. The Royals once envisioned Rosa as a set-up man, but without a reliable second pitch, he could be destined for a career in middle relief.

The Royals must feel like they never have too much depth at shortstop, thus the acquisition of Navarro. In the past decade, they have deployed Yuniesky Betancourt (73 OPS+ for Kansas City), Mike Aviles (98), Tony Pena Jr. (44), Angel Berroa (78), Neifi Perez (45) and Rey Sanchez (71) as regulars at the position. They got career years from Berroa in 2003 (101 OPS+) and Aviles in 2008 (121), but otherwise it's been a sea of light hitting with only occasional defensive excellence. For his part, Navarro spent two seasons in the Rookie-level Pioneer League after being drafted, batting just .254 in 503 at-bats for Missoula. He didn't light up the low Class A Midwest League in his first taste of full-season ball in 2009, batting just .262/.308/.339 in 451 at-bats for South Bend, but he did show a repeatable, line-drive swing from both sides of the plate. He'll need to make more contact, but he hit with more authority in the second half (.362 slugging) and is an above-average runner. Navarro's defensive acumen and versatility will carry him up the ladder. "He has good range to both sides, nimble feet and a solid-average arm," we wrote in our 2010 Prospect Handbook.